Method for establishing ultra-thin gate insulator using oxidized nitride film

Abstract

A method for fabricating a semiconductor device including a silicon substrate includes forming a thin Nitrogen Oxide base film on a substrate, and then depositing an ultra-thin nitride film on the base film. The semiconductor device is then annealed in situ in ammonia, following which the device is oxidized in Nitrogen Oxide. FET gates are then conventionally formed over the gate insulator, and the gates are next implanted with Nitrogen to passivate dangling Nitrogen and Silicon bonds in the nitride, thus decreasing the charge content in the film. Consequently, the resultant gate insulator is electrically insulative without degrading performance with respect to a conventional gate oxide insulator.

What is claimed is:  
     
       1. A method for making a semiconductor device, comprising: 
       providing a semiconductor substrate;  
       establishing a nitride film over the substrate;  
       annealing the substrate with film in ammonia; then  
       oxidizing the substrate with film in Nitrogen Oxide; and  
       forming FET gates on portions of the film.  
     
     
       2. The method of claim  1 , further comprising establishing a Nitrogen Oxide base film on the substrate in contact therewith, prior to establishing the nitride film, the nitride film being deposited on the base film in contact therewith. 
     
     
       3. The method of claim  1 , further comprising implanting Nitrogen into at least some of the gates. 
     
     
       4. The method of claim  2 , wherein the base film defines a thickness of no more than fifteen Angstroms (15 Å). 
     
     
       5. The method of claim  2 , wherein the base film defines a thickness of no more than twelve Angstroms (12 Å). 
     
     
       6. The method of claim  1 , wherein the annealing act is undertaken such that the Nitrogen concentration in the nitride film is greater than the stoichiometric concentration of Nitrogen in the nitride film. 
     
     
       7. The method of claim  1 , wherein the annealing act is undertaken such that dangling Nitrogen and Silicon bonds in the nitride film are passivated to thereby decrease the charge concentration in the nitride film to a charge concentration of a thermal oxide film having the same dimensions as the nitride film. 
     
     
       8. The method of claim  1 , wherein the annealing act is undertaken at temperatures up to eleven hundred degrees Celsius (1100° C.).